Recently interest had increased in thermoplastic resin systems which contain desiccants or other adsorbents, especially where the resulting system is used to deliver an adsorption and/or desiccation function to an environment. This interest is especially apparent in the insulating glass industry where recent technological developments such as those described in U.S. Pat. Nos. 5,313,761 and 5,177,916 have proved to be reliant on the ability to deliver a flowable, adhesive desiccant formulation in the manufacture of insulating glass units.
Various formulations have been proposed to meet the needs of the insulating glass industry. Examples of formulations are disclosed in U.S. Pat. Nos. 5,510,416 and 5,632,122 as well as in PCT Published Application WO 96/08541.
While the existing formulations have significant commercial use, there is a constant desire to improve the formulations by minimizing the amount of resin component needed to deliver and maintain the necessary amount of desiccant in the desired location (e.g. adhered to a U-shaped window spacer).
In meeting the need for higher loading/more efficient formulations, it is generally desirable that the formulations are usable in existing equipment such that the implementation of the formulation would not require any additional expenditure for equipment by the user. Thus, it is highly desirable that the requirements for handling the formulation (i.e. heating, pumping, applying) do not become more severe. This presents a significant challenge in the context of flowable thermoplastic resin systems since the formulation viscosity typically increases sharply as a function of adsorbent loading just above the maximum practical loading for the specific formulation. Thus, simply increasing the amount of adsorbent even in a seemingly minor amount (or decreasing the amount of resin component) would result in a large increase in viscosity for the overall formulation at application temperature.
Additionally, it is desirable that the formulation not present any loss of performance in other aspects which may be important to the specific end use. Thus, where the formulation is to be used in an insulating glass unit such as described in the above mentioned patents, the formulation should resistant to slump and provide adequate adhesion to the window spacer.